Tough or Tender

New technology is on the horizon to more accurately predict the eating quality of beef.It's not difficult for consumers to discern tough from tender when a steak lands on their plate. But for an industry moving toward selling its product based on taste, that's a judgment that comes too late. Unfortunately, tenderness has been an elusive quality for meat scientists to predict.Texas A&M meat scientist

Advertisement

New technology is on the horizon to more accurately predict the eating quality of beef.

It's not difficult for consumers to discern tough from tender when a steak lands on their plate. But for an industry moving toward selling its product based on taste, that's a judgment that comes too late. Unfortunately, tenderness has been an elusive quality for meat scientists to predict.

Texas A&M meat scientist Rhonda Miller blames that on the complexity of meat. "Tenderness is affected by connective tissue and fat as well as the contractive and degraded state of muscle fibers. Trying to measure all of those factors is really difficult."

Marbling, the fat within meat, has long been king in helping determine the expected eating characteristics - tenderness, juiciness and flavor - of the final cooked product. The USDA grading system ranks beef cuts as Select, Choice or Prime based on marbling, with the odds of getting a tough steak decreasing as marbling increases. But it is a method that is subjective at best.

"Marbling only explains about 10 percent of the variation in tenderness," says Duane Wulf, Ohio State University meat specialist.

"Almost no Prime steaks are tough," says Wulf. "The problem is 84 percent of all beef falls within the Select and lower one-third of the Choice marbling range, and marbling in that narrow range doesn't accurately describe tenderness. Low Choice steaks can be tougher than Select ones."

Sorting System To improve consistency, we need a better method of sorting the products we have, says Chris Calkins, University of Nebraska meat scientist.

Consumer satisfaction depends to a large extent on expectations, Calkins says. "If a consumer has high expectations and has an adequate eating experience he can be dissatisfied. Whereas, someone with low expectations who has an adequate eating experience may be satisfied."

Calkins says consumer expectations are the reason there is a market for steaks that range in tenderness, like round steak and tenderloin steak. "People buy round steak, but they know to expect a product that isn't as tender, so they aren't dissatisfied," Calkins says. "We need to be able to give them what they expect," he adds.

And measuring tenderness doesn't just benefit the consumer. In order for true value-based marketing to be realized, the industry must have a reliable measurement of tenderness, Calkins says.

That in mind, meat scientists have been working toward the technology that can predict whether a carcass will be tough or tender. Each technology has its limitations and challenges, and none has been widely accepted throughout the beef industry. Following is a summary of what's on the horizon.

Tenderness Technology * MARC Beef Classification System - Currently, the most accurate method for determining tenderness is a sped up version of the Warner-Bratzler shear force test called the MARC Beef Classification System. Developed by meat scientists Steven Shackelford, Tommy Wheeler and Mohammad Koohmaraie at the U.S. Meat Animal Research Center (MARC) in Clay Center, NE, this technology started as a method to classify tenderness by removing a rib steak from the carcass, rapidly cooking it and measuring shear force. It's a process that takes about 10 minutes but has 90% accuracy at classifying carcasses as tender, intermediate or tough.

Recently, a video image analysis component was added to the tenderness system, according to Shackelford. An image is taken of the rib steak. From that, calculations can be made for carcass cutability, ribeye area and subprimal cut, in addition to tenderness.

"This is probably as accurate as we're ever going to get," says Wulf. "But it's very expensive and it uses a steak out of every carcass. It still would be better to have something that is less expensive and non-invasive (doesn't remove product from the carcass)," he adds.

Researchers at MARC say that its accuracy makes it cost effective. An in-plant version that could categorize 400 head/hour would cost $200,000. "Depending on size, plants could conduct tenderness classification using as little as $35,000 worth of equipment," says Shackelford.

"Relative to the market premiums commanded by high-quality branded beef products, the cost of the MARC Beef Classification System at 10-15 cents/lb. of strip loin or ribeye is very small," says Shackelford.

"We agree that some indirect measures of meat tenderness would be cheaper in the near term, but using less accurate measures simply because they are cheaper may actually be more expensive in the long term when the cost of failing to meet consumer expectations results in further erosion of beef demand," says Shackelford.

Denver-based DM Inc., which slaughters 5,000 head/year, implemented a manual MARC Beef Classification System eight months ago. The company is "ecstatic" with the results, says Tim Amlaw, chief operating officer for the company.

DM Inc. markets Premier Lean, a branded product from double-muscled cattle, to the hotel and restaurant industry and retail markets on both coasts and in the central U.S. Their label carries a Tenderness One classification that Amlaw says guarantees tenderness.

"We only box the carcasses that test 100 percent tender," Amlaw says. That pays off for consumers and producers, he adds.

Since double-muscled cattle have little fat deposition, payment is on a truly value-based system, Amlaw says. "The last load of cattle we slaughtered had 6 of 43 cattle grading Select, the balance graded Standard, but 78 percent graded tender. Because of that, producers were paid 8 cents/lb. above the top of the market," he says.

The PM Beef Group, a Kansas City-based company, is preparing to implement the MARC system as well, MARC's Shackelford says.

*Colorimeter A hand-held device, the colorimeter offers probably the quickest measure of tenderness by sorting beef based on muscle color, according to Ohio State's Wulf.

The colorimeter is used to scan the ribeye to get three readings: L*, which measures colors from white to black, a*, which measures from green to red, and b*, which measures from blue to yellow. The whole process takes about one second, Wulf says.

"We've found that some of these color values are correlated with tenderness," Wulf says. "It seems to pick out carcasses that are a little darker shade as tougher. They aren't dark cutters, but they have a darker shading."

Currently, about 8.3% of Select beef is tough. Sort out the darkest 25% and only 2.7% remains tough, according to Wulf.

This is a non-invasive technique that's very quick and inexpensive, Wulf points out. A colorimeter costs about $6,000.

Research is currently being conducted at Ohio State and Colorado State, where Wulf first started using the colorimeter to predict beef tenderness.

* Connective Tissue (CT) Probe Developed in Canada, the connective tissue probe is being explored by that country as a means of predicting tenderness by correlating connective tissue and palatability.

The probe is inserted into a muscle to measure connective tissue through light fluorescence transmitted through optic fibers. When the probe passes through connective tissue, the tissue fluoresces, sending light back up the fiber. Since the light has a different wave length on the return, a reading can be made to determine the amount of connective tissue and then correlate it to tenderness.

Howard Swatland, University of Guelph, Ontario, meat scientist who developed the probe, admits, "Clearly connective tissue is only one source of toughness, so the probe only works to a certain extent."

The Ontario Cattlemen's Association (OCA) owns the technology and patent for the probe and is currently evaluating the probe's potential as a commercial unit.

"We've taken the original concept and worked on the design to improve its ability to work in a commercial setting," says Bob Richmond, of RMS Research Management Systems Inc., who is working with OCA.

"It appears that it works," Richmond says. Initial studies conducted with the Lacombe Research Center showed correlation of over 90% in predicting shear value, he reports. A large test sampling conducted on the loin has just been completed and results are being analyzed.

Research also indicates the probe may detect tenderness in live animals, thus offering opportunities for future selection and culling. But it is an area that needs further research, Swatland says.

* Elastography Invented in 1991 by the medical field as a method to detect cancerous tumors, elastography takes ultrasound one step further. Ultrasound waves are used to measure the relative hardness or softness of tissue and provide an image of muscle structure. Researchers at Texas A&M are then correlating these measures to meat's tenderness and palatability.

"This is still a fairly young technology," says Texas A&M's Miller. She says elasticity measurements have predicted tenderness with about 40% accuracy.

"The medical field is really excited about this technology. When we apply it to meat, we are on the cutting edge, but we don't know how to interpret all the information we are getting back yet," Miller says.

"It shows some promise, but there are some hurdles," Miller adds. The biggest will be manufacturing electronic equipment that can withstand the harsh environment of a packing plant.

"A colleague of mine often reminds me, 'Remember, there have been two generations of meat scientists who have tried to answer this question. If it were easy, someone would have already come up with the answer,'" says Miller.